Such oscillators may be used in beacons for satellite location, with the oscillator determining the beacon transmitter frequency. Such oscillators tend to be made in hybrid technology.
An oscillator must deliver a signal whose frequency is stable and therefore it must operate at a constant temperature which, in principle, should be its ideal operation temperature.
Further, it must withstand mechanical shocks which may be continuing sinusoidal vibrations of about 5 g, and also shocks of about 100 g which last for a few milliseconds when a beacon is dropped into the sea, for example.
To satisfy all these operating conditions, the oscillator is placed on a mechanical support and covered with a sealed hood.
Said mechanical support performs its mechanical insulation function properly, but known hoods are not good thermal insulators. Heat losses are due partly to conduction phenomena via the mechanical and electrical connections, partly to radiation phenomena (which can be reduced by forming polished surface conditions on the support e.g. by silver coating it), and mainly to convection phenomena which can be reduced by setting up a secondary vacuum of more than 10.sup.-4 torr inside the hood.
A substantially perfect vacuum can be set up by removing the residual gases by means of a gas absorber in the form of a pellet which has a high gas-absorption coefficient. The oscillator must also have a constant frequency as a function of time, i.e. good resistance to aging, low feed current consumption and a low production cost.
A paper by the communications division of Messrs. Bendix, read at the Proceedings of the 34th Annual Frequency Control Symposium USAERADCOM at Fort Monmouth, NJ 07703, in May, 1980, describes an oscillator support used in a satellite intended to be put in orbit. Said oscillator support is constituted by a first container in which the oscillator is suspended but not fixed at its base, said first container being drawn down towards a base fitting by wires which also serve as electric connections. A second container fixed on said base fitting encloses the first container. A secondary vacuum is set up between the two containers to avoid heat losses due to convection phenomena.
Said oscillator support is very complex and the use of two containers makes the support assembly heavier. Then, said support assembly does not dissociate its various functions from one another, namely, mechanical insulation and thermal insulation since the tight wires serve to maintain the first container and also act as electrical connections. The above mixing of functions does not provide optimum mechanical and electrical characteristics.
Preferred embodiments of the present invention remedy these drawbacks, providing an oscillator support which has only one sealed hood or container and having its mechanical and electrical functions performed by distinct means.